The present invention relates generally to the realm of tire changing, where many machines, devices and accessories are designed to assist in making the process of changing a tire less physical and more efficient.
It will be appreciated by those skilled in the art of designing and manufacturing equipment used to change the tubeless tires mounted on the rims of cars, light trucks and other vehicles, that such equipment must perform quickly and efficiently in order to be competitive in the marketplace. Modest improvements in the industry can thus become significant.
The type of equipment for which Applicant's invention is designed is the swing-arm rim-holding tire changer. Examples of such equipment include the tire changers manufactured by Hennessy Industries, Inc., Applicant's Assignee and marketed under the trademarks COATS.TM. and AMMCO.TM., including the COATS.TM. Model 5030A, Model 5060A-E and Model 5060AX-EX. However, there are many manufacturers of such equipment, including FMC Corporation of Chicago, Ill.; Corghi of Correggio, Italy, and SICE of Correggio, Italy. Equipment of this type has been readily available and on the market for many years, is the subject matter of numerous patents and has been described in a variety of publications, bulletins and brochures, operating instructional manuals, and the like. One such machine is illustrated in the design patent issued to Applicant as co-inventor in U.S. Design Pat. No. 293,916.
In the normal tire-changing procedure, the operator places a rim on the table of the rim-holding tire changer, secures the rim to the table, places a tire over the rim, mounts the tire on the rim by using the mount/dismount head to force the bead over the rim, and then fills the air chamber of the tire with air to inflate the tire. In most cases, a tire must first be removed from a rim before installing a new tire. This procedure is described in detail in U.S. patent application Ser. No. 08/516,129, the substance of which is incorporated here and by reference, and which is assigned to the Assignee of the present invention.
The design of wheel and tire configurations constantly changes for many reasons, including improved durability and performance. The equipment used for changing tires must change accordingly in order to accommodate these new designs. The present invention is directed to a device used to assist in the changing of a tire.
Recent innovations in tire design have resulted in wider, lower profile tires with stiffer sidewalls. One such tire is referred to as a "run-flat" tire, which is designed to run for a specified period of time after having been punctured. The characteristics of these tires that make them more durable also make them much more difficult to change due to their increased width and decreased flexibility. Further, changing these tires is a more dangerous operation because the operator must apply a greater force to disengage the tire bead from the rim. These and other considerations must be incorporated into the development and design of more effective, efficient and safe tire changers.
To meet this challenge most manufacturers of tire changers have added powered features to their equipment to assist the operator in dealing with the increasing difficulty of changing a tire. These features include powered arms with attached pivoting devices for pushing against the tire to offset the manual effort required by the operator. Currently, all assist devices on competitor's equipment are designed such that the entire arm mechanism must be moved vertically in order to properly position attachments such as blocks and rollers against the tire surface to perform their specified function. Positioning the entire mechanism can be a cumbersome and time consuming process, particularly when the several tires must be changed.
Most of these arm mechanisms consist of a sliding contact block attached to a jointed arm that moves up and down on a vertical guide that is attached to the chassis of the tire changer. The arm is usually powered by an air cylinder. The contact blocks of devices that are currently available aid only in the separation of an upper tire bead from a tire rim. They do not provide any means for assistance in positioning the demount head. Further, they do not aid in lower bead separation. Finally, tires sometimes explode during the inflation step, and the off-centered support offered by these devices does not provide the most effective explosion restraint.
What is needed is a mechanism having a contact block that can be easily positioned over the tire and then raised and lowered to assist in mounting and demounting activities and that provides superior restraint during inflation of the tire.